Mine, while not a gt3, spins with resistance that builds~20+ftlbs. I asked my dealer tech who called me back saying he just tested a brand new gt3 with the plastic still on, just to be sure.....and it turns as well, he also said it has to be tested under load..... Not sure this 'test' is all that accurate now.
...not sure he's pulling my leg, can somebody with a brand new car with lsd please do this test?
c

 

According to this excellent thread, the shop manual for 996 LSDs states that the still torque should be between 5 to 15 Nm (15 Nm = 11 lbft), which is next to nothing. One can assume that the 997 LSD is not that different.

 

It has been my experience that LSDs need some lode to work at maximum resistance, other wise they would limit ability to rotate well.

 

If we assume that this number is correct for a 997 3, and I suspect it is or its real close, then my car at 8.5 ft lbs is showing some breakdown of the clutch disks. However compared to the aftermarket Guard for example even a new OE unit may only have about 25% or less of the pre load of the Guard Dif.

I am coming to understand that the OE unit is just not that durable for tracking. I have 7500 miles and about 1/2 are track miles, maybe a tad more and Its what I call a track Queen, I get no satisfaction driving it on the street. I have already come to the conclusion that a rebuild is in order. Waiting for a break in the action and Oh ya, and a stimulus check. I think I am still getting some decent lock up but I noticed last year that my inside right rear was wearing faster that the outside left rear, which I thought was odd on a car with LSD, so as you know from my DIY I installed new toe links, because on one of my alignments the right toe was out. I assumed that tire wear was due to toe,

Now I am not so sure. It could have been inside tire spin coming out of the corner. So what to look for then is 1)instability under threshold braking, 2) instability under trail braking, 3) accelerated inside tire wear, 4) and maybe excessive rear pad wear if the ABS is kicking in to compensate.